A memory tag may generally be considered an electronic memory device without an integral power source which needs to be powered to be read or written to. Most conveniently, these may be provided as transponder devices (for example, devices which are inductively powered by radio frequency signals). Memory tags in the form of Radio Frequency Identification (RFID) tags are well known in the prior art. RFID tags come in many forms but all comprise an integrated circuit on which in use data can be stored and a coil which enables it to be interrogated by a reader which also powers it by means of an inductive (wireless) link. Generally RFID tags are quite large, due to the frequency they operate at (13.56 MHz) and the size of coil they thus require, and operate over large ranges and have very small storage capacities. Smaller RFID tags have also been developed, operating at various frequencies, but still having small storage capacities. Some RFID tags include Read Only Memory (ROM) and are written to at the time of manufacture, whilst others have read and write capability. RFID tags have tended to be used in quite simple applications, such as for file tracking within offices or in place of or in addition to bar codes for produce identification and supply chain management.
One use to which such RFID tags can be put is the annotation of items, such as documents, with data over and above that printed on them. For example in EP 1 076 316 A2 Eastman Kodak Company describe the use of an RFID tag of conventional form secured to a print, being an output image on a substrate, possibly of a photograph. The kind of data which it is envisaged will be stored in the RFID tag on the print relates to the manner in which the print has been processed, particularly if the print is an output sheet from a proofing system. In any event the examinations of data given range from 8 buts to 256 bits. A technique is described for communicating with multiple prints within range of the transceiver used to communicate with them, such as for example if a single print needs to be located amongst a file of such prints.
The present invention seeks to provide an improved method for annotation of items, such as documents, and apparatus for doing so.